Summer is already at its best, but unfortunately, my solar system (of the garden house) is not performing as it should. The battery is never at the predicted state of charge, and somehow, all performance is looking pretty much off the earlier predictions and calculations. Why is that? Well, first, checked the charge controller, but all seems fine. Next, the two solar panels (about 100 W each), and to my greatest dissatisfaction, one of the modules is only giving 8 Volts, rather than about 16-18 Volts, in full sun, and with no load connected. That’s not good.

A few days later, a big, flat box arrived –

– with a 140 Watt polycrystalline solar panel! Quite affordable, just about EUR 115.

Quite beautiful to look at, especially, at the current and power information.

Mounted it on the roof – there is still plenty of space, but one module will be good for now.

Below you can see both the new and old modules. One of old modules (the polycrystalline module) has been disconnected – I will leave it on the roof for now, at least it is shielding it from the rain.

Updated simulation – with an assumed, generous power usage. Seems we should be good even in winter. But let’s find out later this year!